1. Field of the Invention
The present invention relates to a wireless tag communication control device that enables most suitable communication when persons or objects having attached thereto a wireless tag pass through a communication gate that is placed at various facilities.
2. Description of the Related Art
In sorting persons or objects for transport which go into or go out of managed areas of various facilities, in various fields, there is widely utilized a system of attaching a wireless tag having stored therein inherent ID data to persons or objects in advance, and communicating with the wireless tag by transmitting an electric wave from an antenna installed at a gateway or a delivery path. On the other hand, distances between wireless tags and an antenna are coming to be elongated, and the output of an electric wave transmitted from an antenna is coming to be increased so as to ensure the communication.
However, an intensive electric wave having increased power is not desirable for persons in health, and there may be raised an adverse affect of bringing about a malfunction on various peripheral information processing devices. Furthermore, so as to cope with the situation in which visitation of persons cannot be predicted and the situation in which objects are transported in a random manner, a powerful electric wave is always transmitted from an antenna, which further enhances the anxiety of adverse affect due to such electric wave. So, there is a known technique of arranging a sensor for sensing visitation of persons before an antenna for communicating with wireless tags, halting the electric wave transmission from the antenna until the sensor senses a person, and starting the electric wave transmission from the antenna after the sensor senses a person (Jpn. Pat. Appln. Laid-Open Publication No. 2000-20648).
Employing the known method, since the electric wave transmission from the antenna is halted until the sensor senses a person, energy can be saved and an adverse affect exerted on peripheral information processing devices is reduced. On the other hand, since an electric wave of a predetermined output has to be always transmitted so that the communication can be properly performed after a person is sensed, it is difficult to remove the adverse affect by an electric wave radiated on persons.